What should be the minimum thickness of exterior walls prior to applying dampproofing?

The correct choice regarding the minimum thickness of exterior walls prior to applying dampproofing is indeed 3/8 inch. This thickness is significant because it provides a robust substrate that can effectively support the dampproofing layer while also ensuring proper adhesion. A wall thickness of at least 3/8 inch is generally deemed sufficient to resist moisture penetration while allowing the dampproofing materials to perform their intended function of preventing moisture from rising through the wall assembly.

When applying dampproofing, it's crucial to consider the wall thickness because insufficient thickness could result in inadequate bonding and might diminish the performance of the dampproofing system over time. Inadequately thick walls may also be more susceptible to damage and moisture infiltration, leading to potential structural issues.

This standard ensures that the wall can accommodate the stresses from moisture movement and provides a suitable surface for the bonding of dampproofing materials, ultimately enhancing the durability and moisture resistance of the building envelope.